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DOE OSTI2023

Efficient Fast Fractionation of Biomass Using a Diol-Based Deep Eutectic Solvent for Facilitating Enzymatic Hydrolysis and Obtaining High-Quality Lignin

Current DES pretreatment is often performed under relatively severe conditions with high temperature, long time, and high DES usage. This work studied a short-time diol DES (deep eutectic solvent) pretreatment under mild conditions to fractionate the bamboo, facilitate enzymatic hydrolysis, and obtain high-quality lignin. At an optimized condition of 130 °C for only 10 min, lignin and xylan removal reached 61.34% and 84.15 %, with residual glucan showing a ~90% enzymatic hydrolysis yield. Equally important, the dissolved lignin could be readily recovered with 97.51% yield, exhibiting 96.65 % β-O-4 preservation. The fractionation and lignin protection mechanisms were unveiled by XRD, FTIR, cellulose-DP, 2D HSQC NMR, 31 P NMR and GPC analysis. Finally, this study highlighted that short-time fractionation of bamboo can be achieved by a diol-based DES which is an ideal strategy to upgrade the lignocellulose biomass for high enzymatic hydrolysis yields and high-quality lignin stream.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Measurements of the branching fraction ratio $$ \mathcal{B}\left(\phi \to {\mu}^{+}{\mu}^{-}\right)/\mathcal{B}\left(\phi \to {\textrm{e}}^{+}{\textrm{e}}^{-}\right) $$ with charm meson decays

Abstract Measurements of the branching fraction ratio$$ \mathcal{B}\left(\phi \to {\mu}^{+}{\mu}^{-}\right)/\mathcal{B}\left(\phi \to {e}^{+}{e}^{-}\right) $$ B ϕ → μ + μ − / B ϕ → e + e − with$$ {D}_s^{+}\to {\pi}^{+}\phi $$ D s + → π + ϕ andD + → π + ϕdecays, denoted$$ {R}_{\phi \pi}^s $$ R ϕπ s and$$ {R}_{\phi \pi}^d $$ R ϕπ d , are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4 fb −1 ofppcollision data collected with the LHCb experiment. The branching fractions are normalised with respect to theB + →K + J/ψ(→e + e − ) andB + →K + J/ψ(→μ + μ − ) decay modes. The combination of the results yields$$ {R}_{\phi \pi}=1.022\pm 0.012\left(\textrm{stat}\right)\pm 0.048\left(\textrm{syst}\right). $$ R ϕπ = 1.022 ± 0.012 stat ± 0.048 syst . The result is compatible with previous measurements of theϕ→ℓ + ℓ − branching fractions and predictions based on the Standard Model.

Physics↗

DOE OSTI2020

Measurement of quark- and gluon-like jet fractions using jet charge in PbPb and pp collisions at 5.02 TeV

The momentum-weighted sum of the electric charges of particles inside a jet, known as jet charge, is sensitive to the electric charge of the particle initiating the parton shower. This paper presents jet charge distributions in $ \sqrt{s_{\mathrm{NN}}} $ = 5.02 TeV lead-lead (PbPb) and proton-proton (pp) collisions recorded with the CMS detector at the LHC. These data correspond to integrated luminosities of 404 μb$^{−1}$ and 27.4 pb$^{−1}$ for PbPb and pp collisions, respectively. Leveraging the sensitivity of the jet charge to fundamental differences in the electric charges of quarks and gluons, the jet charge distributions from simulated events are used as templates to extract the quark- and gluon-like jet fractions from data. The modification of these jet fractions is examined by comparing pp and PbPb data as a function of the overlap of the colliding Pb nuclei (centrality). This measurement tests the color charge dependence of jet energy loss due to interactions with the quark-gluon plasma. No significant modification between different centrality classes and with respect to pp results is observed in the extracted quark- and gluon-like jet fractions.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

Precise measurements of branching fractions for $ {\mathrm{D}}_{\mathrm{s}}^{+} $ meson decays to two pseudoscalar mesons

We measure the branching fractions for seven $D$$^{+}_{s}$ two-body decays to pseudo-scalar mesons, by analyzing data collected at √s = 4.178 ~ 4.226 GeV with the BESIII detector at the BEPCII collider. The branching fractions are determined to be $$ {\displaystyle \begin{array}{c}\mathcal{B}\left({D}_s^{+}\to {K}^{+}\eta \hbox{'}\right)=\left(2.68\pm 0.17\pm 0.17\pm 0.08\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to \eta \hbox{'}{\pi}^{+}\right)=\left(37.8\pm 0.4\pm 2.1\pm 1.2\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}^{+}\eta \right)=\left(1.62\pm 0.10\pm 0.03\pm 0.05\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to \eta {\pi}^{+}\right)=\left(17.41\pm 0.18\pm 0.27\pm 0.54\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}^{+}{K}_S^0\right)=\left(15.02\pm 0.10\pm 0.27\pm 0.47\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}_S^0{\pi}^{+}\right)=\left(1.109\pm 0.034\pm 0.023\pm 0.035\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}^{+}{\pi}^0\right)=\left(0.748\pm 0.049\pm 0.018\pm 0.035\right)\times {10}^{-3},\end{array}} $$ B D s + → K + η ' = 2.68 ± 0.17 ± 0.17 ± 0.08 × 10 - 3 , B D s + → η ' π + = 37.8 ± 0.4 ± 2.1 ± 1.2 × 10 - 3 , B D s + → K + η = 1.62 ± 0.10 ± 0.03 ± 0.05 × 10 - 3 , B D s + → η π + = 17.41 ± 0.18 ± 0.27 ± 0.54 × 10 - 3 , B D s + → K + K S 0 = 15.02 ± 0.10 ± 0.27 ± 0.47 × 10 - 3 , B D s + → K S 0 π + = 1.109 ± 0.034 ± 0.023 ± 0.035 × 10 - 3 , B D s + → K + π 0 = 0.748 ± 0.049 ± 0.018 ± 0.035 × 10 - 3 , where the first uncertainties are statistical, the second are systematic, and the third are from external input branching fraction of the normalization mode $ {D}_s^{+} $ D s + → K + K - π + . Precision of our measurements is significantly improved compared with that of the current world average values.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2024

Improved measurement of the branching fraction of hc → γη′/η and search for hc → γπ0

Abstract The processesh c → γP(P=η′, η, π 0 ) are studied with a sample of (27.12±0.14)×10 8 ψ(3686) events collected by the BESIII detector at the BEPCII collider. The decayh c → γηis observed for the first time with the significance of 9.0σ, and the branching fraction is determined to be (3.77±0.55±0.13±0.26)×10 −4 , while$$ \mathcal{B} $$ B (h c → γη′) is measured to be (1.40±0.11±0.04±0.10)×10 −3 , where the first uncertainties are statistical, the second systematic, and the third from the branching fraction ofψ(3686)→ π 0 h c . The combination of these results allows for a precise determination of$$ {R}_{h_c}=\frac{\mathcal{B}\left({h}_c\to {\pi}^0\gamma \eta \right)}{\mathcal{B}\left({h}_c\to {\pi}^0\gamma {\eta}^{\prime}\right)}, $$ R h c = B h c → γη B h c → γ η ′ , which is calculated to be (27.0±4.4±1.0)%. The results are valuable for gaining a deeper understanding ofη − η′ mixing, and its manifestation within quantum chromodynamics. No significant signal is found for the decayh c →γπ 0 , and an upper limit is placed on its branching fraction of$$ \mathcal{B} $$ B (h c →γπ 0 )<5.0×10 −5 , at the 90% confidence level.

Physics↗

DOE OSTI2022

Amplitude analysis and branching fraction measurement of the decay $\mathrm{D}_s^+$ → $\mathrm{K}^+π^+π^-π^0$

The singly Cabibbo-suppressed decay D$^+_s$ → K + π + π - π 0 is observed by using a data set corresponding to an integrated luminosity of 6.32 fb -1 recorded by the BESIII detector at the centre-of-mass energies between 4.178 and 4.226 GeV. The first amplitude analysis of D$^+_s$ → K + π + π - π 0 reveals the sub-structures in this decay and determines the fractions and relative phases of different intermediate processes. The dominant intermediate process is D$^+_s$ → K *0 ρ + , with a fit fraction of (40.5 ± 2.8 stat. ± 1.5 syst. )%. With the detection efficiency based on our amplitude analysis, the absolute branching fraction for D$^+_s$ → K + π + π - π 0 is measured to be (9.75 ± 0.54 stat. ± 0.17 syst. ) x 10 -3 .

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2023

Charm production and fragmentation fractions at midrapidity in pp collisions at $\sqrt{\textrm{s}}$ = 13 TeV

Measurements of the production cross sections of prompt $D^{0}$, $D^{+}$, $D^{*+}$, $D^{+}_{s}$, $Λ^{+}_{c}$, and $Ξ^{+}_{c}$ charm hadrons at midrapidity in proton-proton collisions at $\sqrt{\textrm{s}}$ = 13 TeV with the ALICE detector are presented. The D-meson cross sections as a function of transverse momentum (p T ) are provided with improved precision and granularity. The ratios of p T -diferential meson production cross sections based on this publication and on measurements at diferent rapidity and collision energy provide a constraint on gluon parton distribution functions at low values of Bjorken-x (10 —5 –10 —4 ). The measurements of $Λ^{+}_{c}$ ($Ξ^{+}_{c}$) baryon production extend the measured p T intervals down to p T = 0(3) GeV/c. These measurements are used to determine the charm-quark fragmentation fractions and the $c$$\overline{c}$ production cross section at midrapidity (|$y$| < 0.5) based on the sum of the cross sections of the weakly-decaying ground-state charm hadrons $D^{0}$, $D^{+}$, $D^{+}_{s}$, $Λ^{+}_{c}$, and $Ξ^{0}_{c}$ and, for the first time, $Ξ^{+}_{c}$, and of the strongly-decaying J/ψ mesons. The frst measurements of $Ξ^{+}_{c}$and $Σ^{0,++}_{c}$ fragmentation fractions at midrapidity are also reported. A signifcantly larger fraction of charm quarks hadronising to baryons is found compared to e + e — and ep collisions. The $c$$\overline{c}$ production cross section at midrapidity is found to be at the upper bound of state-of-the-art perturbative QCD calculations

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

NMR relaxometry characterization of water adsorption in corn stover anatomical fractions

Nuclear magnetic resonance (NMR) relaxometry is applied to provide direct measurement of water adsorption in anatomical fractions of corn stover. NMR transverse T 2 relaxation time distribution measurements indicate multiple water populations, which vary with anatomical fraction and water adsorption. Measured T 2 data are used to calculate thermodynamic properties of Brunauer-Emmet-Teller adsorption theory using a model to estimate mono and bilayer relaxation. T 2 data are used directly to determine rotational diffusion correlation times indicating adsorption interaction strength. T 1 -T 2 longitudinal-transverse relaxation time correlation measurements quantify differences in the molecular level structural order of the adsorbate surface water as a function of water activity, i.e. relative humidity or water vapor partial pressure. The T 1 /T 2 ratio provides a measure of the surface energy related to the adsorption strength and surface diffusive mobility of the water adsorbate and differentiates the anatomical fractions. Furthermore, the results indicate that direct measurement of NMR relaxation times can be used to characterize corn stover biomass water adsorption, data relevant to processing and handling considerations.

09 BIOMASS FUELS↗

DOE OSTI2020

Evaluation of near-ambient algal biomass fractionation conditions for bioproduct development

This contribution describes an algal fractionation scheme based on cell lysing and carbohydrate hydrolysis under acidic conditions, coupled with solvent extraction, that produces algal lipids, carbohydrates, and proteinaceous solid from partially dewatered algal biomass. Here, a design of experiments analysis was employed to identify the effect of fractionation conditions on the yields of the three product streams. By selection of appropriate conditions, the process can be steered from simple lipid extraction to near complete fractionation of the biomass. Lipid purification and upgrading were respectively achieved with a low-cost adsorbent and an inexpensive Ni-based catalyst that deoxygenated the lipids via decarboxylation/decarbonylation, an approach offering several advantages over the hydrodeoxygenation-based processes typically employed to convert lipids to hydrocarbons. The proteinaceous solids obtained were found to have much lower ash content as well as higher protein content relative to the untreated algae, enhancing the suitability of this material as a feedstock for the production of bioplastics.

09 BIOMASS FUELS↗

DOE OSTI2021

Severity factor kinetic model as a strategic parameter of hydrothermal processing (steam explosion and liquid hot water) for biomass fractionation under biorefinery concept

Hydrothermal processes are an attractive clean technology and cost-effective engineering platform for bio-refineries based in the conversion of biomass to biofuels and high-value bioproducts under the basis of sustainability and circular bioeconomy. The deep and detailed knowledge of the structural changes by the severity of biomasses hydrothermal fractionation is scientifically and technological needed in order to improve processes effectiveness, reactors designs, and industrial application of the multi-scale target compounds obtained by stream explosion and liquid hot water systems. The concept of the severity factor [log 10 (R 0 )] established > 30 years ago, continue to be a useful index that can provide a simple description of the relationship between the operational conditions for biomass fractionation in second generation of biorefineries. Furthermore, this review develops a deep explanation of the hydrothermal severity factor based in lignocellulosic biomass fractionation with emphasis in research advances, pretreatment operations and the applications of severity factor kinetic model.

09 BIOMASS FUELS↗

DOE OSTI2022

Effective biomass fractionation and lignin stabilization using a diol DES system

A sustainable and renewable biorefinery will increase the economic viability of lignocellulose-derived products. In this study, a diol-based deep eutectic solvent (DES) was developed to reduce the recalcitrance of bamboo, facilitate saccharification and valorize the lignin fraction. The DES pretreatment dramatically enhanced glucan digestibility by the effective removal of lignin (as high as 85.45%) and xylan (91.12%). Notably, the recovered lignin from DES pretreatment was protected during the fractionation, showing well-preserved β-O-4 structures (31.82%–59.06%). The mechanism of lignin protection was analyzed to be accomplished by incorporating the diol hydroxyl functional groups into the α position of the lignin β-O-4 structure via etherification. This work highlighted that diol DES is a promising pretreatment solvent to valorize both cellulose and lignin fractions with high enzymatic hydrolysis yield and high-quality lignin co-product.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Examining the effects of chemical cleaning, leaching, and partial dissolution on zinc and cadmium isotope fractionation in marine carbonates

The application of zinc (Zn) and cadmium (Cd) isotopes as palaeo-proxies in carbonate sediment is rapidly expanding due to their potential for tracing changes in biological productivity in the modern and past oceans. However, there are limited investigations into the chemical cleaning methods required to produce the most consistent and accurate data for these novel isotope systems. This could impact their use as palaeo-proxies to reconstruct ocean-atmosphere-climate interactions throughout Earth's history. To address this concern and expand the utility of the Zn and Cd stable isotope systems as palaeo-productivity tracers, the performance of two standard chemical cleaning protocols for acquiring robust and reliable Zn and Cd isotope datasets were assessed. These include (i) the Cd-cleaning method that uses a reductive step to selectively leach contaminating secondary iron (Fe)-manganese (Mn) (oxyhydr)oxide coatings from the carbonate surface, and an oxidative step that is used to remove post-depositional organic matter and sulphide precipitates; and (ii) the magnesium/calcium cleaning protocol that includes an oxidative step only, leaving secondary Fesingle bondMn (oxyhydr)oxide coatings largely intact. Well-preserved Holocene-, and Mesozoic-aged carbonate sediments were used to test the reliability of these two chemical cleaning methods. The Holocene samples comprised not only aliquots of bulk sediment, but also individual species of planktic and benthic foraminifera. Our results show that the best practice chemical cleaning method for retrieving consistent and accurate Zn and Cd isotope, and Zn/Ca and Cd/Ca datasets for carbonate sediments, requires both reductive and oxidative cleaning following the Cd-cleaning method. This differs from most methodological approaches applied to date that remove the reductive step from the chemical cleaning protocol and apply an oxidative step only, or no chemical cleaning at all. Inclusion of the reductive step in the chemical cleaning method typically shifts δ 66 Zn by ~0.1‰ lower and δ 114 Cd by 0.3‰ higher in the solid phase, while Zn/Ca and Cd/Ca typically decrease 2-fold. The benthic foraminifera, C. wuellerstorfi, that live in ocean bottom waters where the seawater Zn and Cd isotope composition is homogeneous display evidence of Zn and Cd isotope fractionation between seawater and carbonate on the order of 0.08 ± 0.08‰ (2SE, n = 4) and -0.25 ± 0.13‰ (2SE, n = 4), respectively, in agreement with experimental constraints. Furthermore, evidence of Zn isotope fractionation effects are recorded in a naturally-dissolved carbonate sediment, together with laboratory-controlled carbonate dissolution experiments. Based on these results, we recommend the Cd-cleaning method and the application of Zn and Cd isotope fractionation factors to accurately reconstruct past seawater Zn and Cd isotope compositions from carbonate sediments.

58 GEOSCIENCES↗

DOE OSTI2022

Te(IV) immobilization by siderite: Reaction kinetics, mechanism, and Te isotopic fractionation

Mining and industrial use over recent decades have released tellurium (Te) into the environment where it potentially contaminates soils, water supplies and food sources. Therefore, it is important to find ways of removing mobile and bioavailable Te from aqueous environments. Here, we report aqueous Te(IV) removal by siderite at varying Te concentrations (2, 6 and 10 mg mL –1 Te(IV)) and pH values (7, 7.9 and 9), together with associated isotope fractionation (ε 130 Te/ 125 Te). Our results show effective immobilization of Te(IV) that follows pseudo-first order rate kinetics. Formation of magnetite indicates reduction of Te(IV) on siderite surfaces and the formation of Te(0). The overall isotope fractionation (ε) is small (–0.23 ± 0.06‰) providing evidence that it is primarily controlled by adsorption of Te(IV) occurring simultaneously with reduction of Te(IV). Therefore, Te(IV) removal by siderite under mildly reducing ferruginous conditions may be identifiable by the characteristically small isotopic fractionation during both natural attenuation and active remediation. To our knowledge, this is the first study reporting reaction mechanisms of Te(IV) immobilization by an environmentally relevant Fe(II) mineral.

58 GEOSCIENCES↗

DOE OSTI2020

Evaluation of semi-empirical soot models for nonpremixed flames with increased stoichiometric mixture fraction and strain

Due to the size and complexity of industrial-scale systems and computing limitations, semi-empirical soot models are often employed in CFD simulations rather than computationally-expensive detailed models. Many of these models were developed for specific applications with unique characteristic timescales and/or validated only under fuel-air combustion conditions. Hence, their use in different contexts, such as oxy-combustion, could lead to inaccurate predictions. In this study, twelve semi-empirical models (1-step or 2-step) are evaluated on their ability to respond to changes in stoichiometric mixture fraction (Z st ) and strain in a series of ethylene counterflow flames which span the experimental sooting-to-non-sooting (yellow to blue) transition. A unique approach of plotting soot formation rate in normalized, local equivalence ratio space is introduced to aid in the analysis. Results show that no existing model is able to predict a blue flame when Z st is increased beyond the experimentally-measured sooting limit. Many models give the counter-intuitive result of increasing peak and/or integrated soot volume fraction (svf) as Z st increased, contrary to experimental observations. Two models are able to successfully predict a blue flame upon increase of strain to the sooting limit value. For two-step models, the strong dependence of growth rate on surface area results in high sensitivity of svf to changing flame boundary conditions, but with mixed accuracy. There is still a significant need for a robust semi-empirical model which can accurately predict soot fraction in systems with oxygen-enrichment or variable strain.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Ignition delay times of NH 3 /DME blends at high pressure and low DME fraction: RCM experiments and simulations

Here, autoignition delay times of ammonia/dimethyl ether (NH 3 /DME) mixtures were measured in a rapid compression machine with DME fractions of 0, 2 and 5 and 100% in the fuel. The measurements were performed at equivalence ratios $\varphi$= 0.5, 1.0 and 2.0 and pressures in the range 10–70 bar; depending on the fuel composition, the temperatures after compression varied from 610 K to 1180 K. Admixture of DME is seen to have a dramatic effect on the ignition delay time, effectively shifting the curves of ignition delay vs. temperature to lower temperatures, up to ~250 K compared to pure ammonia. Two-stage ignition is observed at $\varphi$= 1.0 and 2.0 with 2% and 5% DME in the fuel, despite the pressure being higher than that at which pure DME shows two-stage ignition. At $\varphi$= 0.5, a reproducible pre-ignition pressure rise is observed for both DME fractions, which is not observed in the pure fuel components. A novel NH 3 /DME mechanism was developed, including modifications in the NH 3 subset and addition of the NH 2 + CH 3 OCH 3 reaction, with rate coefficients calculated from ab initio theory. Simulations faithfully reproduce the observed pre- ignition pressure rise. While the mechanism also exhibits two-stage ignition for NH 3 /DME mixtures, both qualitative and quantitative improvement is recommended. The overall ignition delay times for ammonia/DME mixtures are predicted well, generally being within 50% of the experimental values, although reduced performance is observed for pure ammonia at $\varphi$= 2.0. Simulating the ignition process, we observe that the DME is oxidized much more rapidly than ammonia. Analysis of the mechanism indicates that this ‘early DME oxidation’ generates reactive species that initiate the oxidation of ammonia, which in turn begins heat release that raises the temperature and accelerates the oxidation process towards ignition. The reaction path analysis shows that the low-temperature chain-branching reactions of DME are important in the early oxidation of the fuel, while the sensitivity analysis indicates that several reactions in the oxidation of DME, including cross reactions between DME and NH 3 species presented here, are critical to ignition, even at fractions of 2% DME in the fuel.

10 SYNTHETIC FUELS↗

DOE OSTI2021

End-gas autoignition fraction and flame propagation rate in laser-ignited primary reference fuel mixtures at elevated temperature and pressure

Knock in spark-ignited (SI) engines is initiated by autoignition of the unburned gasses upstream of spark-ignited, propagating, turbulent premixed flames. Knock propensity of fuel/air mixtures is typically quantified using research octane number (RON), motor octane number (MON), or methane number (MN; for gaseous fuels), which are measured using single-cylinder, variable compression ratio engines. In this study, knock propensity of SI fuels was quantified via observations of end-gas autoignition (EGAI) in unburned gasses upstream of laser-ignited, premixed flames at elevated pressures and temperatures in a rapid compression machine. Stoichiometric primary reference fuel (PRF; n-heptane/isooctane) blends of varying reactivity (50 ≤ PRF ≤ 100) were ignited using an Nd:YAG laser over a range of temperatures and pressures, all in excess of 545 K and 16.1 bar. Laser ignition produced outwardly-propagating premixed flames. High-speed pressure measurements and schlieren images indicated the presence of EGAI. The fraction of the total heat release attributed to EGAI (i.e., EGAI fraction) varied with fuel reactivity (i.e., octane number) and the time-integrated temperature of the end-gas prior to ignition. Flame propagation rates, which were measured using schlieren images, were only weakly correlated with octane number but were affected by turbulence caused by variation in piston timing. Under conditions of low turbulence, measured flame propagation rates approached one-dimensional premixed laminar flame speed computations performed at the same conditions. Experiments were simulated with a three-dimensional CONVERGE™ model using reduced chemical kinetics (121 species, 538 reactions). The simulations accurately captured the measured flame propagation rates, as well as the variation in EGAI fraction with fuel reactivity and time-integrated end-gas temperature. The simulations also revealed low-temperature heat release as well as formaldehyde and hydrogen peroxide formation in the end-gas upstream of the propagating flame, which increased the temperature and degree of chain branching in the end-gas, ultimately leading to EGAI.

42 ENGINEERING↗

DOE OSTI2022

Corrosion-resistant polyurethane coatings from structure-homogenized biorefinery lignin through fractionation and oxypropylation

Using lignin for polyurethane (PU) synthesis is challenging because of its heterogeneous structure, i.e., broad molecule weight (MW) distribution and diverse hydroxyl (OH) functionality. This complexity influences the crosslinking reaction between lignin and isocyanate and affects the quality of PU products. Here, we propose a two-step strategy for lignin structure homogenization by lowering its MW and uniforming OH functionality (step 2). Step 1 involves a bioethanol fractionation process, yielding fractionated lignin with one order lower MW than the raw lignin while exhibiting better processability for the subsequent process. Step 2 is performed by an oxyalkylation process using fractionated lignin that converts phenolic and carboxylic OHs to aliphatic OHs. As a result, we obtained structure-homogenized lignin with good compatibility and crosslinking with hexamethylene diisocyanate for PU coating synthesis. Moreover, PU coatings prepared from structure-homogenized lignin display a defect-free microscopic structure and show better corrosion resistance than coatings fabricated from its raw lignin alternative. Overall, the structure homogenization process is a beneficial way of using lignin as biopolyol in PU synthesis toward the application-oriented design of corrosion-resistant lignin-based PU coatings.

36 MATERIALS SCIENCE↗

DOE OSTI2020

An arbitrarily high-order three-dimensional Cartesian-grid method for reconstructing interfaces from volume fraction fields

Here Tthis work describes a newly developed, arbitrarily high-order Cartesian-grid method for reconstructing material interfaces from a volume fraction field. The method begins by identifying all of the grid cells in the volume fraction field that are intersected by the interface and need to be approximated by the reconstruction scheme. Finite-differences are used to calculate the gradient of the volume fraction field and provide an estimate of the surface normal in all of the interfacial grid cells. Groups of connected grid cells are then identified which all have the same dominant component of the normal vector. This grouping by orientation determines the proper dependent variable to use in the surface reconstruction (e.g. for a 2D curve, this step determines if the surface will be approximated by a function of x or y). A cumulative integral over the surface is constructed and fit using b-splines for two-dimensional problems or tensor-product b-splines for three-dimensional problems. This construction allows for the interface to be recovered through application of the second fundamental theorem of calculus. Fitting the cumulative integral with $\mathscr{N}$ th-order b-splines (or tensor-product b-splines) yields an ($\mathscr{N}$-1) th-order convergence rate of the interface shape. Differentiation of the b-spline interface function(s) allows for the high-order approximation of the normal vector and curvature to be obtained directly anywhere along b-spline. Together, the proposed reconstruction technique can achieve arbitrarily high mesh convergence rates. Validation tests are presented with mesh convergence rates ranging from fourth- to tenth-order.

97 MATHEMATICS AND COMPUTING↗